Eating a well-balanced diet is something that we all know we should do to make sure we stay healthy, but what does this actually mean and how does this relate to both our mood and our ability to think and process information in our daily lives? Western diets can often include over consumption of energy-dense but nutrient-poor ultra-processed foods, including highly processed cereal grains and processed meat products high in saturated fats. Long-term consumption of this kind of diet results in‘hidden hunger’: a deficiency in vitamins and minerals.

To many people a well-balanced diet means making sure that there is the right balance of protein, carbohydrate and fats (macronutrients) in our meals, and that we need to eat at least five servings of fruit and vegetables. What we are perhaps less aware of is making sure that there are all the vitamins and minerals our bodies need in what we eat. According to the World Health Organization there are19 essential vitamins and minerals(micronutrients); vitamins A, C, D, E and K, all the B-group vitamins (8 in total), and the minerals calcium, iodine, iron, magnesium, selenium, and zinc.

These micronutrients are termed ‘essential’ as the human body is unable to synthesise them itself and must therefore be obtained through diet or supplements. Vitamin D is the exception to this as the majority ofVitamin D is synthesised in the body following exposure to sunlight; in the Northern Hemisphere 10–15 minutes of sun exposure on the arms and legs each day in the summer months is enough, however sunscreen may prevent UVB rays reaching the skin. Insufficient levels of sunshine in the winter and low levels in food means that many people are vitamin D deficient.

The recommended daily intake (RDI) of vitamins and minerals are set ataverage daily requirementssufficient to meet the nutrient requirement of nearly all healthy individuals in a group, for example, the adult RDI of Vitamin C is 90mg/day for men and 75mg/day for women. This level of Vitamin C will prevent the disease of insufficiency, scurvy; but is not set at a level for optimum health simply because this is not known. This is the same for all micronutrients; levels to prevent diseases of insufficiency are known, as are the levels above which toxic effects are seen, but theoptimum level of each micronutrient for human health is not currently understood. This is particularly relevant to my area of research; supplementation with micronutrients for brain health and repair after injury.

Many micronutrients, including the B-complex vitamins, iron, magnesium and selenium, are involved inenergy productioneither through metabolism of macronutrients so they can be utilised, or as part of cellular energy production within mitochondria (the cell’s ‘battery’). These processes are key to providing a foundation to optimal functioning of the brain. Also key to neural function and balanced mood state is the role micronutrients play in synthesis of neurotransmitters including dopamine and serotonin particularly B6, B9 (folate), calcium and iron.

Following brain injury, either trauma or stroke, a number of events occur that have a negative effect on neurons including bleeding (haematoma), oxidative stress, swelling (oedema), and in the case of trauma damage to axons (the brain’s communication pathways) and their insulating covering, myelin.Vitamin Khas been shown to repair blood vessels, reduce the formation of blood clot and swelling, as well as improve blood flow to areas of damage following brain injury. Vitamins C, E, B2 (riboflavin), B6, D and selenium are all able to reduce oxidative stress, mainly through antioxidant properties.

Myelin is vital for efficient communication within the brain, and a number of micronutrients are involved in its formation, integrity and repair. Within the brain, oligodendrocytes (a glial cell), forms myelin by wrapping its processes around axons. This occurs in a predetermined pattern during development, however myelin can be repaired following illness (e.g., multiple sclerosis) or injury. Biotin (B7), B12, Vitamin A, Vitamin K, selenium and iron are all involved in myelin synthesis, maintenance and repair, for example biotin supplementation has been shown to improve symptoms inmultiple sclerosis.

This just a snapshot into the vital role micronutrients play in the body and brain. Insufficient levels of micronutrients also have a detrimental effect on theimmune system, gene expression ofDNA and RNA,bone strengthand blood cell synthesis. There is a long-standing debate around whether multivitamin/mineral supplementsare helpful, harmful, or a waste of money. As with most things in life it may be a case of all things in moderation; many people have diets containing insufficient levels of some micronutrients so taking a broad-spectrum supplement once a day is unlikely to do you harm. On the flip side, taking a handful of pills without the input of a medical professional isn’t to be recommended.

Rebecca Denniss is a doctoral researcher and associate lecturer at Sheffield Hallam University. Her current research focus is to improve the long-term cognitive outcomes for individuals sustaining traumatic brain injuries, whether it is through better understanding of brain changes, improved rehabilitation strategies or micronutrient interventions. More broadly, she is interested in neurodegenerative processes and associated cognitive deficits. Follow her on twitter @Neuro_Ceutical